iMovie for iPhone...can't select transition

Hello JayDar1968,

Looks like you having issues transitioning between your video clips using your iPhone. An update has been released. Updating can help with most irregularities the device is experiencing. Please back up your device and update it to iOS 15.4.1. Check out these steps on how to update your device:

"Update your iPhone, iPad, or iPod touch wirelessly:

1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see two software update options available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.

You might see that your device is up to date and that there's an upgrade available. For example, even if your device is up to date with the latest version of iOS 14, there might be an option to upgrade to iOS 15. You might want to upgrade iOS when you pair an accessory with iPhone."

For additional information, check out these links.

Back up your iPhone: How to back up your iPhone, iPad, and iPod touch - Apple Support

Update your iPhone: Update your iPhone, iPad, or iPod touch - Apple Support

Let us know if you are still experiencing the same issue after you update.

Kindest regards!